1 University of Pittsburgh, Scaife Hall, Suite 818, 3550 Terrace St.,
Pittsburgh, PA 15261
2 T10, MS K710, Los Alamos National Laboratory, Los Alamos, NM 87545
Drug resistance is the inevitable consequence of incomplete suppression of HIV replication. The rapid replication rate of HIV and its inherent genetic variation have led to the identification of many HIV variants that exhibit altered drug susceptibility. The growing number of drug resistance mutations listed in the revised HIV drug resistance database stands as a testimony to the genetic flexibility of HIV. This table, updated in February 2007, lists 947 HIV-1 mutation/drug combinations, of which 37 occur in Gag (including this year, 3 in capsid and 3 in SP-1), 321 in Protease, 9 in Integrase, 374 in RT, and 206 in Env. Although the tables are quite comprehensive, the reader should be reminded that the HIV-1 mutations described are predominantly found in clade B virus and not in other HIV genotypes. Thirty-one mutations in HIV-2 RT and 27 in HIV-2 Protease are listed in the table. In addition, 2 mutations in SIV RT are listed.
The column "Selected or Cross-R" describes how the mutations have been identified. "Selected" refers specifically to mutations identified by in vitro passage of virus in increasing concentrations of a compound, or by sequencing isolates from patients on a specific drug therapy. "Cross-R" (cross-resistance) means that virus with a mutation has been shown to have decreased susceptibility to a compound even though selection of the mutation by the compound has not been reported. The "in vitro" column has a "Y" (for yes) when resistance or cross-resistance to the compound is seen using cloned virus or in cell culture studies; the "in vivo" column has a "Y" (for yes) when resistance or cross-resistance to the compound is seen in patients.
In the "Amino Acid Change" column a + means amino acids have been inserted into the sequence, while a Delta indicates a deletion. In the "Drug Class" column, "NRTI" refers to nucleoside or nucleotide reverse transcriptase inhibitors, while non-nucleoside or HIV-1 specific RT inhibitors are called "NNRTI." The abbreviation MN stands for "Multiple Nucleoside" and refers to resistance to combinations of NRTIs. "MDR" or multi-drug resistant is noted in the "Compound" column if a mutation causes resistance to multiple compounds. Other abbreviations are listed in a separate Abbreviations Table.